Consolidated Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 31, 2015	$ 685,900	$ 50,441,464	$ (37,279,069)	$ 53,258,126	$ (683,956)	$ 66,422,465
Net income				5,594,011		5,594,011
Other comprehensive income (loss)					(625,285)	(625,285)
Dividends on common stock				(1,504,855)		(1,504,855)
Treasury stock purchased			(371,538)			(371,538)
Stock award plans		26,463	347,319			373,782
Stock options exercised	1,650	84,150				85,800
Balance at Dec. 31, 2016	687,550	50,552,077	(37,303,288)	57,347,282	(1,309,241)	69,974,380
Net income				5,157,664		5,157,664
Other comprehensive income (loss)					1,103,048	1,103,048
Dividends on common stock				(1,857,456)		(1,857,456)
Stock award plans		288,722	177,747			466,469
Stock options exercised	300	15,270				15,570
Reclassification of amounts within AOCI to retained earnings due to tax reform				31,818		31,818
Balance at Dec. 31, 2017	687,850	50,856,069	(37,125,541)	60,679,308	(206,193)	74,891,493
Net income				7,331,879		7,331,879
Other comprehensive income (loss)					(246,563)	(246,563)
Dividends on common stock				(2,181,500)		(2,181,500)
Stock award plans		362,636	154,417			517,053
Stock options exercised	2,350	163,880				166,230
Balance at Dec. 31, 2018	$ 690,200	$ 51,382,585	$ (36,971,124)	$ 65,829,687	$ (452,756)	$ 80,478,592